Apologies, I omitted two use statements in the above hitFbNew subroutine, amended as follows:

sub hitFbNew {
  my ($method, $endpoint, $form) = (shift, shift, shift);
  use WWW::Curl::Easy;
  use WWW::Curl::Form;
  my $curl = WWW::Curl::Easy->new;
  my $curlf = WWW::Curl::Form->new;
...
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