how python handle parametric polymorphic function?

Question

• I tried to discover polymorphic sum function in python for 5 variable types : str, int, float, complex, bool.

Here it's the working solution i found:

sum("W", "T", "F") #return WTF
sum(1, 2, 3) #return 6

@staticmethod
def sum(a: None, b: None, c: None) -> object:         
    return a + b + c 

• I tried two other ways, but they don't work as expected.

First way, Python don't recognize the type : It just calls the last sum function and return error

sum("W", "T", "F") #*TypeError: unsupported operand type(s) for +=: 'int' and 'str'*

@staticmethod
def sum(*args: str) -> str:
    sum_str = ""
    for el_str in args:
        sum_str = sum_str + el_str
    return sum_str
@staticmethod
def sum(*args: int) -> int:
    sum = 0
    for el_int in args:
        sum += el_int
    return sum
@staticmethod    
def sum(*args: float) -> float:
    sum = 0
    for el_float in args:
        sum += el_float
    return sum
@staticmethod        
def sum(*args: complex) -> complex:
    sum = 0
    for el_complex in args:
        sum += el_complex
    return sum
@staticmethod
def sum(*args: bool) -> bool:
    sum = 0
    for el_bool in args:
        sum += el_bool
    return sum

Second way, it partially works but I can't support str and number at the same time.

sum("W", "T", "F") #return WTF
sum(1, 2, 3) #return 6

def sum_generic(*args: T) :
    sum_gen = 0 #sum_gen = ""
    for el in args:
        sum_gen = sum_gen + el
    return sum_gen

Questions:

• Why first way doesn't work as expected?
• In the second way, how can I assign the right type to sum_gen ? Like sum_gen: type(args[0])