Print a text formatted to look like a heading.

    The output looks like:
    ===> text
    with marker='=' right now.

    :param str text: the text to echo
    :param str marker: the marker to mark the heading
    :param str marker_color: one of ('black' | 'red' | 'green' | 'yellow' | 'blue' | 'magenta' | 'cyan' | 'white')

def echo_heading(text, marker='=', marker_color='blue'):
    """Print a text formatted to look like a heading.

    The output looks like:
    ===> text
    with marker='=' right now.

    :param str text: the text to echo
    :param str marker: the marker to mark the heading
    :param str marker_color: one of ('black' | 'red' | 'green' | 'yellow' | 'blue' | 'magenta' | 'cyan' | 'white')
    """
    click.secho(marker * 3 + '>', fg=marker_color, nl=False)
    click.echo(' ' + text)