input: Write a function to search for a character in a given string. If the character is found in the string, return True; otherwise, return False.
  assert serach_char("Hello", 'l')==True
  assert serach_char("Hello", 'o')==True
  assert serach_char("Hello", 'z')==False
  assert serach_char("", 'a')==False
output: def search_char(s, c):
      return c in s