input: Write a python function to convert a string to its hexadecimal representation.
  assert text_to_hex("Hello World") == '48656c6c6f20576f726c64'
  assert text_to_hex("Python") == '507974686f6e'
  assert text_to_hex("123") == '313233'
output: def text_to_hex(text):
      return text.encode('utf-8').hex()