def get_google_key(key_dir="."):
    """
    Grabs the Google Maps API key from a file.

    This is kept locally on my machine so I don't expose it on Github.

    Function assumes the key is kept in a file called 'keys.txt'.

    Parameters
    ----------

    key_dir: String. Optional, default "." 
        Directory that contains the file with key. 

    Returns
    ----------

    key: String. Required.
        The Google Maps API key.
    """
    
    fname = "{0}/keys.txt".format(key_dir)
   
    with open(fname, "r") as f:
        key = f.read()

    return key