# a general structure for a seach

SEARCH: while ( 1 ) {

    # keep searching until we find what we want or discover it
    # isn't there

    # stop if the thing we are looking cannot be found
    if ( search space is empty ) {
            # thing we are looking for is not present
            last SEARCH;
        }

    # probe the search space, that is, pick a spot in the search 
    # space and take a look

    # stop if we find it
    if ( thing found ) {
            # thing we are looking for is present
            last SEARCH;
        }

    # narrow down the search space and keep looking

    }