my $cu1 = $umls->getConceptList($t1); #calling function from umls::similarity #ERRRO 1 as mentioned
 my $cui1 =pop @{$cu1};
 my $cu2 = $umls->getConceptList($t2);***error
 my $cui2 = pop @{$cu2};
 print $cui1;    # ****ERROR2 unintialized $cui1
 my $lvalue = $lch->getRelatedness($cui1, $cui2);