Athletics – World Athletics Championships – women's 50 km walk victory ceremony – The Mall, London, Britain – August 13, 2017 – Hang Yin (silver) of China, Ines Henriques (gold) of Portugal and Shuqing Yang (bronze) of China pose with medals. REUTERS/Toby Melville

Athletics – World Athletics Championships – women's 50 km walk victory ceremony – The Mall, London, Britain – August 13, 2017 – Hang Yin (silver) of China, Ines Henriques (gold) of Portugal and Shuqing Yang (bronze) of China pose with medals. REUTERS/Toby Melville

A student paints the yin-yang symbol on his friend's cheek to mark International Day of Peace in Kathmandu September 21, 2010. REUTERS/Shruti Shrestha (NEPAL - Tags: SOCIETY)

A priest reads as he waits at a desk behind red lanterns at the Qingyanggong Taoist Temple in the south-western Chinese city of Chengdu, Szechuan province September 17, 2007. The temple is the oldest in the Chengdu area, dating back to around 620AD during the Tang Dynasty of. REUTERS/David Gray (CHINA)

People practice Taiji, a form of Chinese martial arts, underneath an Yin and Yang sign in Havana's Chinatown April 3, 2007. REUTERS/Claudia Daut (CUBA)

Acrobats from the Great Chinese State Circus perform during their show 'Yin Yang' in Burgos, northern Spain April 20, 2006. The Circus is more than 2,000 years old, with artists beginning studies at the age of six to become talented performers from 10 -18 years of age. The circus, featuring about 60 acrobats, is directed by gymnast Li Xining and is currently touring Spain. Picture taken April 20, 2006. REUTERS/Felix Ordonez

Acrobats from the Great Chinese State Circus perform during their show 'Yin Yang' in Burgos, northern Spain April 20, 2006. The Circus is more than 2,000 years old, with artists beginning studies at the age of six to become talented performers from 10 -18 years of age. The circus, featuring about 60 acrobats, is directed by gymnast Li Xining and is currently touring Spain. Picture taken April 20, 2006. REUTERS/Felix Ordonez

A woman from the Great Chinese State Circus performs during their show 'Yin Yang' in Burgos, northern Spain April 20, 2006. The Circus is more than 2,000 years old, with artists beginning studies at the age of six to become talented performers from 10 -18 years of age. The circus, featuring about 60 acrobats, is directed by gymnast Li Xining and is currently touring Spain. Picture taken April 20, 2006. REUTERS/Felix Ordonez

A member from the Great Chinese State Circus performs during their show 'Yin Yang' in Burgos, northern Spain April 20, 2006. The Circus is more than 2,000 years old, with artists beginning studies at the age of six to become talented performers from 10 -18 years of age. The circus, featuring about 60 acrobats, is directed by gymnast Li Xining and is currently touring Spain. Picture taken April 20, 2006. REUTERS/Felix Ordonez

Acrobats from the Great Chinese State Circus perform during their show 'Yin Yang' in Burgos, northern Spain April 20, 2006. The Circus is more than 2,000 years old, with artists beginning studies at the age of six to become talented performers from 10 -18 years of age. The circus, featuring about 60 acrobats, is directed by gymnast Li Xining and is currently touring Spain. Picture taken April 20, 2006. REUTERS/Felix Ordonez

Acrobats from the Great Chinese State Circus perform during their show 'Yin Yang' in Burgos, northern Spain April 20, 2006. The Circus is more than 2,000 years old, with artists beginning studies at the age of six to become talented performers from 10 -18 years of age. The circus, featuring about 60 acrobats, is directed by gymnast Li Xining and is currently touring Spain. Picture taken April 20, 2006. REUTERS/Felix Ordonez

A woman from the Great Chinese State Circus performs during their show 'Yin Yang' in Burgos, northern Spain April 20, 2006. The Circus is more than 2,000 years old, with artists beginning studies at the age of six to become talented performers from 10 -18 years of age. The circus, featuring about 60 acrobats, is directed by gymnast Li Xining and is currently touring Spain. Picture taken April 20, 2006. REUTERS/Felix Ordonez

An actor and actresses perform in the Korean show 'Yin Yang' at the X Iberoamerican Theater Festival in Bogota, Colombia, April 6, 2006. Over 100 theatre companies will present their shows from March 31 to April 16. REUTERS/Daniel Munoz

An actor performs in the Korean show 'Yin Yang' at the X Iberoamerican Theater Festival in Bogota, Colombia, April 6, 2006. Over 100 theatre companies will present their shows from March 31 to April 16. REUTERS/Daniel Munoz

An actress performs in the Korean show titled 'Yin Yang' at the X Iberoamerican Theater Festival in Bogota, Colombia April 6, 2006. Over 100 theatre companies will present their shows from March 31 to April 16. REUTERS/Daniel Munoz

An actor perform in a Korean show titled 'Yin Yang' at the X Iberoamerican Theater Festival in Bogota, Colombia April 6, 2006. Over 100 theatre companies will present their shows from March 31 to April 16. REUTERS/Daniel Munoz

An actress performs in the Korean show titled 'Yin Yang' at the X Iberoamerican Theater Festival in Bogota, Colombia April 6, 2006. Over 100 theatre companies will present their shows from March 31 to April 16. REUTERS/Daniel Munoz

An acrobat from the Great Chinese State Circus performs during a rehearsal for their new attraction called 'Yin Yang' in Coruna. An acrobat from the Great Chinese State Circus performs during a rehearsal for their new attraction called 'Yin Yang' in the northern Spanish town of Coruna April 6, 2005. The Chinese Circus is over 2,000-year old with artists beginning studies at the age of three to become talented performers at 10-12 years. Picture taken April 6, 2005 REUTERS/Miguel Vidal

Acrobats from the Great Chinese State Circus perform during the rehearsal of their new attraction called "Yin Yang" in the northern Spanish town of Coruna April 6, 2005. The Chinese Circus is over 2,000-year old with artists beginning studies at the age of three to become talented performers at 10-12 years. Picture taken April 6, 2005 REUTERS/Miguel Vidal MV/ACO/DY

Acrobats from the Great Chinese State Circus perform during the rehearsal of their new act called 'Yin Yang' in the northern Spanish town of Coruna, late April 6, 2005. The Chinese Circus is over 2,000-years old with artists beginning studies at the age of three to become talented performers at 10-12 years. Picture taken April 6, 2005. REUTERS/Miguel Vidal MV/ACO

Acrobats from the Great Chinese State Circus perform during the rehearsal of their new act called 'Yin Yang' in the northern Spanish town of Coruna, late April 6, 2005. The Chinese Circus is over 2,000-years old with artists beginning studies at the age of three to become talented performers at 10-12 years. Picture taken April 6, 2005. REUTERS/Miguel Vidal MV/ACO

Acrobats from Great Chinese State Circus perform during the rehearsal of their new act called 'Yin Yang' in the northern Spanish town of Coruna, late April 6, 2005. The Chinese Circus is over 2,000-years old with artists beginning studies at the age of three to become talented performers at 10-12 years. Picture taken April 6, 2005. REUTERS/Miguel Vidal MV/ACO

Acrobats from Great Chinese State Circus perform during the rehearsal of their new attraction called 'Yin Yang ' in the northern Spanish town of Santander, late March 16, 2005. The Chinese Circus is over 2,000-year old with artists beginning studies at the age of three to become talented performers at 10-12 years.REUTERS/Victor Fraile SP/WS

Acrobats from Great Chinese State Circus perform during the rehearsal of their new attraction called 'Yin Yang ' in the northern Spanish town of Santander, late March 16, 2005. The Chinese Circus is over 2,000-year old with artists beginning studies at the age of three to become talented performers at 10-12 years.REUTERS/Victor Fraile SP/WS

Chinese worshippers pray in front of a 'yin yang' symbol at a temple to celebrate the Lunar New Year in Shanghai February 13, 2005. The Chinese continued to enjoy their annual week-long Spring Festival holiday to celebrate the Year of the Rooster by visiting temples, parks, shopping malls and homes of relatives. REUTERS/Claro Cortes IV CC/SA

Chinese worshippers pray in front of a "yin yang" symbol at a temple to celebrate the Lunar New Year in Shanghai February 13, 2005. The Chinese continue to enjoy their annual Lunar New Year holiday to celebrate the Year of the Rooster by visiting temples, parks, shopping malls and visiting relatives. REUTERS/Claro Cortes IV CC/YH

Ping Zhang, a licensed acupuncturist, prepares her patient Barbara Leivent for face lift treatment at her office in Port Washington New York October 28, 2004. Chinese Acupuncture Face Lift is based on the traditional Chinese medicine healing theory that the face is the place where the essence of "yin" organs and energy of "yang" organs merge together via energy channels called "meridians." The face is the only place where all 14 different meridians either end or start from. The acupuncture face lift works by inserting fine needles on the point from different meridians on the body,face,ear, scalp and local problem areas according to each individuals condition of imbalances. REUTERS/Shannon Stapleton SS

Ping Zhang, a licensed acupuncturist, shows the various energy channels involved in the acupuncture face lift treatment at her office in Port Washington New York October 28, 2004. Chinese Acupuncture Face Lift is based on the traditional Chinese medicine healing theory that the face is the place where the essence of "yin" organs and energy of "yang" organs merge together via energy channels called "meridians." The face is the only place where all 14 different meridians either end or start from. The acupuncture face lift works by inserting fine needles on the point from different meridians on the body,face,ear, scalp and local problem areas according to each individuals condition of imbalances. REUTERS/Shannon Stapleton SS

Ping Zhang, a licensed acupuncturist, applies acupuncture needles to her patient Barbara Leivent for a face lift treatment at her office in Port Washington New York October 28, 2004. Chinese Acupuncture Face Lift is based on the traditional Chinese medicine healing theory that the face is the place where the essence of "yin" organs and energy of "yang" organs merge together via energy channels called "meridians." The face is the only place where all 14 different meridians either end or start from. The acupuncture face lift works by inserting fine needles on the point from different meridians on the body, face, ear, scalp and local problem areas according to each individuals condition of imbalances. REUTERS/Shannon Stapleton SS

Barbara Leivent, a patient of Ping Zhang, a licensed acupuncturist, rests with acupuncture needles on her face during a face lift treatment at Zhang's office in Port Washington, New York October 28, 2004. Chinese Acupuncture Face Lift is based on the traditional Chinese medicine healing theory that the face is the place where the essence of "yin" organs and energy of "yang" organs merge together via energy channels called "meridians." The face is the only place where all 14 different meridians either end or start from. The acupuncture face lift works by inserting fine needles on the point from different meridians on the body, face, ear, scalp and local problem areas according to each individual's condition of imbalances. HALTH REUTERS/Shannon Stapleton SS

Recording artist Yin Yang Twins arrives for the Source Hip-Hop Music Awards in Miami, Florida October 10, 2004. Dozens of recording artists took part in the annual ceremony. REUTERS/Gary I. Rothstein JLS