def _get_color_definitions(data):
    """Returns the list of custom color definitions for the TikZ file.
    """
    definitions = []
    fmt = '\\definecolor{{{}}}{{rgb}}{{' + ','.join(3 * [data['float format']]
        ) + '}}'
    for name, rgb in data['custom colors'].items():
        definitions.append(fmt.format(name, rgb[0], rgb[1], rgb[2]))
    return definitions
