input: Write a function to search for a character in a given string.
  def search_char(input_str, char):
    return char in input_str
  
  assert search_char("Hello", 'l')==True
  assert search_char("Hello", 'o')==True
  assert search_char("Hello", 'z')==False
  assert search_char("", 'a')==False
output: def search_char(input_str, char):
    return char in input_str