Finding all the terms and relationships in a given ontology

## Finding and getting elements (e.g. terms, relationships)

1. Find all the terms in a given ontology.
2. Find all the relationships in a given ontology.
3. Find all the terms using a regular expression for the ID.
4. Get a specific term by name.
5. Get a specific term by ID.

1. Find all the terms in a given ontology:

       			use OBO::Parser::OBOParser;

       			my $my_parser = OBO::Parser::OBOParser->new();
       			my $ontology = $my_parser->work("gene_ontology_edit.obo");

       			my @my_terms = @{$ontology->get_terms()}; # get all the terms

       			foreach my $t (@my_terms) {
       				print "The name of the term is: ", $t->name(), ", and its ID is:", $t->id(), "\n";
       			}

2. Find all the relationships in a given ontology:

       			use OBO::Parser::OBOParser;

       			my $my_parser = OBO::Parser::OBOParser->new();
       			my $ontology = $my_parser->work("my_obo_ontology.obo");

       			my @my_rels= @{$ontology->get_relationships()}; # get all the relationships

       			foreach my $r (@my_rels) {
       				print "The ID of the relationhip is: ", $r->id();
       			}

3. Find all the terms using a regular expression for the ID:

       			use OBO::Parser::OBOParser;

       			my $my_parser = OBO::Parser::OBOParser->new();
       			my $ontology = $my_parser->work("my_obo_ontology.obo");

       			my @my_terms = @{$ontology->get_terms("APO:G.*")}; # get all the terms with such an ID

       			foreach my $t (@my_terms) {
       				print "The name of the term is: ", $t->name();
       			}

4. Get a specific term by name:

       			use OBO::Parser::OBOParser;

       			my $my_parser = OBO::Parser::OBOParser->new();
       			my $ontology = $my_parser->work("my_obo_ontology.obo");

       			my $my_term = $ontology->get_term_by_name("protein"); # get the term by name

       			print "The ID of my term is: ", $t->id();

5. Get a specific term by ID:

       			use OBO::Parser::OBOParser;

       			my $my_parser = OBO::Parser::OBOParser->new();
       			my $ontology1 = $my_parser->work("go.obo");
       			my $ontology2 = $my_parser->work("apo.obo");

       			my $my_term1 = $ontology1->get_term_by_id("GO:00007049"); # get the term by ID
       			my $my_term2 = $ontology2->get_term_by_id("APO:P0000056"); # get the term by ID

       			print "\nThe name of the term1 is: ", $my_term1->name();
       			print "\nThe name of the term2 is: ", $my_term2->name();