Creates a rst.sty Latex string representation of a standard RST relation
    (one nucleus, one satellite).

def make_nucsat(relname, nuc_types, elements):
    """Creates a rst.sty Latex string representation of a standard RST relation
    (one nucleus, one satellite).
    """
    assert len(elements) == 2 and len(nuc_types) == 2, \
        "A nucsat relation must have two elements."
    assert set(nuc_types) == set(['N', 'S']), \
        "A nucsat relation must consist of one nucleus and one satellite."
 
    result = "\dirrel"
    for i, nuc_type in enumerate(nuc_types):
        if nuc_type == 'N':
            result += '\n\t' + NUC_TEMPLATE.substitute(nucleus=elements[i])    
        else:
            result += '\n\t' + SAT_TEMPLATE.substitute(satellite=elements[i], relation=relname)
    return result