input: Write a python function to sort a list of strings by their first character.
  assert sort_list_by_first_char(["banana", "apple", "cherry"]) == ["apple", "banana", "cherry"]
  assert sort_list_by_first_char(["zebra", "elephant", "dog"]) == ["dog", "elephant", "zebra"]
  assert sort_list_by_first_char(["pear", "grape", "apple"]) == ["apple", "grape", "pear"]
output: def sort_list_by_first_char(strings):
      return sorted(strings, key=lambda x: x[0])