(pattern, string)
return backtrack(pattern, string, {})
:type pattern: str
    :type string: str
    :rtype: bool
:type pattern: str
    :type string: str
    :rtype: bool
: type pattern : str : type string : str : rtype : bool
def pattern_match(pattern, string):
    """
    :type pattern: str
    :type string: str
    :rtype: bool
    """
    return backtrack(pattern, string, {})
def pattern_match ( pattern , string ) : return backtrack ( pattern , string , { } )