<human>:  how to change character in a string using replace function.
<bot>: Here is a Python program to change character in a string using replace

import re

def replace_character(string, character, replacement):
  """
  move to util_iter
  """
  return string.replace(character, replacement)

# Enter the string
string = "cat"

# Enter the character
character = "a"

# Enter the replacement
replacement = "b"

# Calling the function
print((replace_character(string, character, replacement)))

#Example Output
# cbt

#Remember to inspect code for bugs.