input: Write a python function to read the content of a file and return it as a string.
  assert read_file("/path/to/file.txt") == "Expected file content"
  assert read_file("/path/to/emptyfile.txt") == ""
  assert read_file("/path/to/nonexistentfile.txt") is None
output: def read_file(file_path):
      try:
          with open(file_path, 'r') as file:
              return file.read()
      except FileNotFoundError:
          return None