def _fips_cleaner(code):
    """Standardizes county FIPS codes as 5-digit strings.

    Parameters
    ----------
    code : pandas.Series object
      A series containing FIPS codes as string, int, or float type.
    
    Returns
    ----------
    pandas.Series
    """
    return code.astype(str).str.extract('(^[^/.]*).*', expand=False).str.zfill(5)