<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def _FormatPropertyName(self, property_name):
 """Formats a camel case property name as snake case. Args: property_name (str):
 property name in camel case. Returns: str: property name in snake case. """

    # TODO: Add Unicode support.
    fix_key = re.sub(r'(.)([A-Z][a-z]+)', r'\1_\2', property_name)
    return re.sub(r'([a-z0-9])([A-Z])', r'\1_\2', fix_key).lower()