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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def to_snake(camel):
 """TimeSkill -> time_skill"""

    if not camel:
        return camel
    return ''.join('_' + x if 'A' <= x <= 'Z' else x for x in camel).lower()[camel[0].isupper():]