Python-сообщество

input = "my_str+---=()" 
result = "";
for char in input:
   if Char_in_A_Z_upper(char): result = result + char; 
   if Char_in_0_9(char): result = result + char; 
   if Char_in_a_z_lower(char): result = result + char; 
   if Char_in_additional(char): result = result + char;

Str = "string_te+-===st"
def char_in_range(AChar, AFirstChar,ALastChar):
  Range = " ".join(map(chr, range(ord(AFirstChar),ord(ALastChar)+1)))
  for Char in Range:
     if Char == AChar: return True     
  return False
result = " "
for char in Str:
  if char_in_range(char, '0', '9'):
      result = result + char
  if char_in_range(char, 'A', 'Z'):
      result = result + char
  if char_in_range(char, 'a', 'z'):
      result = result + char
  if char == "\\":
      result = result + char
  if char == "_":
      result = result + char
  if char == " ":
      result = result + char
print(result)
>>> ================================ RESTART ================================
>>> 
 string_test

''.join(re.findall(r'[a-zA-Z0-9\\ _]', input))

re.sub(r'[^a-zA-Z0-9\\ _]', '', input)