hello monks! Below I have posted my code. I am getting an error which says "Undefined subroutine &main::fields called at test.pl line 34, <$data> line 2." Can anyone help me? 

#Written by Prasuna Dahal

use warnings;
use XML::Simple;
use LWP::UserAgent;
use HTTP::Request::Common;
use URI::Escape;
use Text::CSV;
use Data::Dumper;

my $i = 0;
my @keystr;
my @kwrds = {"inhibitors", "activity", "complex", "activator", "activi
+ty", "activities", "activated", "proteins", "deficiency", "levels", "
+functions", "reductions", "protease", "proteases"};
my $file = "proteinlist.csv";
my $ua = LWP::UserAgent->new;
my $csv = Text::CSV->new({sep_char => ','});

#Open the result in a CSV file
open (my $fh, ">", "test1.csv");
print $fh "Valid Proteins\n";

#open file containig protein_name
#open(my $data1, '<', "proteinlist.csv");

#Open the file containing the PubMed IDs
open(my $data, '<', "test.csv");
while (my $line = <$data>) {
chomp $line;

if ($csv->parse($line)) {
    #Skip 1st line
    next if ($. == 1);

    my @fields = $csv-fields();
    #Replace (-) with (,)
    $fields[0] =~ tr/-/,/;
    my $id = $fields[0];

    #Initialize http request
    my $args = "db=pubmed&id=$id&retmode=text&rettype=abstract";
    my $req = new HTTP::Request POST => 'https://eutils.ncbi.nlm.nih.g
+ov/entrez/eutils/efetch.fcgi';
    $req->content_type('application/x-www-form-urlencoded');
    $req->content($args);

    #Get response
    my $response = $ua->request($req);
    my $content = $response->content;
    
    $fields[0] =~ tr/,/-/;

    my @abstract = split (/[.]/, $content);
    for $abstract(@abstract){
        @var1 = split ((/[ ]|[,]/), $abstract);
        foreach $var1(@var1){
            open(my $data1, "<", $file);
            while (my $line1 = <$data1>) {
                chomp $line1;
                my @fields1 = split ",", $line1;
                $keystr[$i] = $fields1[0];
                $i++;
                if ($var1=~ /\b$keystr[$i]\b/i){
                    foreach $kwrds(@kwrds){
                        if ($var1=~ /\b$kwrds\b/i){
                            my $valid_prot = $var1;
                            }
                        }
                        print $fh "$valid_prot\n";
                        print "$valid_prot\n";
                        }
                    }
                }
            }    
        }
    }
close($fh);

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In reply to Undefined Subroutine error by pdahal

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