def build_transmitter_name(network_name, site_name):
    """
    Return a string that is the network name with spaces removed followed 
    by an underscore followed by the site name with spaces removed.

    EXAMPLES:

    >>> build_transmitter_name('Slap hAppy', 'Go go ')
    'SlaphAppy_Gogo'
    """
    return network_name.replace(' ', '') + '_' + site_name.replace(' ', '')
