def count(lbls, wntarget):
    """
    Count the number of line transitions with wavenumber smaller than wntarget.

    Parameters
    ----------
    lbls: List of lbl objects
    wntarget: Float
        The target wavenumber.

    Returns
    -------
    nwave: Integer
        The number of transitions with wavenumber smaller than wntarget.
    """
    nwave = 0
    for lbl in lbls:
        nwave += lbl.bs(wntarget, 0, lbl.nlines-1)
    return nwave