def METHOD_NAME(abbreviation):
    """
        Constructs proper SPARQL Prefix String for given namespace abbreviation.
        Arguments:
            abbreviation - namespace abbreviation to construct SPARQL PREFIX string for.
        Returns:
            SPARQL query prefix string in the form "PREFIX ns: <full IRI>".
    """
    # Define global scope for global variables
    global PREFIXES
    # Raise key error if given namespace abbreviation has not been specified
    if abbreviation not in PREFIXES.keys():
        raise KeyError('Prefix: "' + abbreviation + '" has not been specified')
    # Get full IRI from pre-specified prefixes dictionary
    iri = PREFIXES[abbreviation]
    if not iri.startswith('<'):
        iri = '<' + iri
    if not iri.endswith('>'):
        iri = iri + '>'
    return 'PREFIX ' + abbreviation + ': ' + iri + ' '