strip.py

from string import whitespace

def rstrip(str):
    i = len(str)
    
    if i != 0:
        while str[i - 1] in whitespace and (i := i - 1):
            pass
    
    return str[:i]

def lstrip(str):
    i = 0
    ei = len(str)
    
    if ei != 0:
        while str[i] in whitespace and (i := i + 1) != ei:
            pass
    
    return str[i:]

def strip(str):
    ei = len(str)
    i1 = 0
    i2 = ei
    
    if ei != 0:
        while str[i1] in whitespace and (i1 := i1 + 1) != ei:
            pass
            
        while str[i2 - 1] in whitespace and (i2 := i2 - 1):
            pass
    
    return str[i1:i2]