def build_splat_az(transmitter):
    """
    Return the text (string) content of a SPLAT! azimuth file (AZ file) corresponding to the given transmitter.

    INPUT:
        - ``transmitter``: dictionary of the same form as any one of the elements in the list output by :func:`read_transmitters`

    OUTPUT:
        String

    NOTES:
        A transmitter with no ``'bearing'`` or ``'horizontal_beamwidth'`` data will produce the string ``'0  0'``.
    """
    t = transmitter
    try:
        bearing = float(t['bearing'])
        hb = float(t['horizontal_beamwidth'])
        left = int(round(360 - (hb/2)))
        right = int(round(hb/2))
        s = '{!s}\n'.format(bearing)
        for x in range(360):
            if left <= x or x <= right:
                normal = 0.9
            else:
                normal = 0.1
            s += '{!s}  {!s}\n'.format(x, normal)
    except:
        s = '0  0\n'

    return s[:-1]