- Added the Array and Hash .fetch() methods to fetch a value with a…

… default value.

Example:
	var a = [3,9,27]
	say a.fetch(2, 42);	# fetches index 2 and prints: 27
	say a.fetch(3, 42);	# fails to fecth index 3, therefore prints: 42

lib/Sidef/Types/Array/Array.pm

@@ -526,6 +526,11 @@ package Sidef::Types::Array::Array {
         exists($self->[$index]) ? $self->[$index] : ();
     }
 
+    sub fetch {
+        my ($self, $index, $default) = @_;
+        exists($self->[$index]) ? $self->[$index] : $default;
+    }
+
     sub _slice {
         my ($self, $from, $to) = @_;
 

lib/Sidef/Types/Hash/Hash.pm

@@ -44,6 +44,11 @@ package Sidef::Types::Hash::Hash {
         exists($self->{$key}) ? $self->{$key} : ();
     }
 
+    sub fetch {
+        my ($self, $key, $default) = @_;
+        exists($self->{$key}) ? $self->{$key} : $default;
+    }
+
     sub slice {
         my ($self, @keys) = @_;
         $self->new(map { ($_ => exists($self->{$_}) ? $self->{$_} : undef) } @keys);