input: Write a python function to find and replace a pattern in a given text using regular expressions.
  assert find_and_replace("He is an excellent programmer", r"excellent", "brilliant") == "He is an brilliant programmer"
  assert find_and_replace("The quick brown fox", r"quick", "slow") == "The slow brown fox"
  assert find_and_replace("Hello, world!", r"world", "universe") == "Hello, universe"
output: import re
  
  def find_and_replace(text, pattern, replacement):
      return re.sub(pattern, replacement, text)