(s, t)
return True
:type s: str
    :type t: str
    :rtype: bool
:type s: str
    :type t: str
    :rtype: bool
: type s : str : type t : str : rtype : bool
def is_isomorphic(s, t):
    """
    :type s: str
    :type t: str
    :rtype: bool
    """
    if len(s) != len(t):
        return False
    dict = {}
    set_value = set()
    for i in range(len(s)):
        if s[i] not in dict:
            if t[i] in set_value:
                return False
            dict[s[i]] = t[i]
            set_value.add(t[i])
        else:
            if dict[s[i]] != t[i]:
                return False
    return True
def is_isomorphic ( s , t ) : if len ( s ) != len ( t ) : return False dict = { } set_value = set ( ) for i in range ( len ( s ) ) : if s [ i ] not in dict : if t [ i ] in set_value : return False dict [ s [ i ] ] = t [ i ] set_value . add ( t [ i ] ) else : if dict [ s [ i ] ] != t [ i ] : return False return True