input: Write a python function to generate combinations of first and last names.
  assert generate_names(['John', 'Emma'], ['Smith', 'Jones']) == ['John Smith', 'John Jones', 'Emma Smith', 'Emma Jones']
  assert generate_names(['Sarah'], ['Brown', 'Robinson']) == ['Sarah Brown', 'Sarah Robinson']
  assert generate_names(['Liam', 'Noah'], ['Wilson']) == ['Liam Wilson', 'Noah Wilson']
output: def generate_names(first_names, last_names):
      return [f"{first} {last}" for first in first_names for last in last_names]