Enables translators to read values from files.

    The value can be referred to with the `file://` prefix. ie:

        conf_key: ${kms file://kms_value.txt}

def read_value_from_path(value):
    """Enables translators to read values from files.

    The value can be referred to with the `file://` prefix. ie:

        conf_key: ${kms file://kms_value.txt}

    """
    if value.startswith('file://'):
        path = value.split('file://', 1)[1]
        config_directory = get_config_directory()
        relative_path = os.path.join(config_directory, path)
        with open(relative_path) as read_file:
            value = read_file.read()
    return value