import re


def is_in_file(path, search_string):
    """
    Determine whether a string is contained in a file.

    Like ``grep``.

    Parameters
    ----------
    path : str
      The path to a file.
    search_string : str
      The string to be located in the file.

    """
    with open(path, 'r') as filep:
        for line in filep:
            if re.search(search_string, line):
                return True
    return False