first array element. This checks to see if the given key is a valid
field in the pseudo-hash.
- exists $phash->[0]{pants}; # true, 'pants' is a valid field
+ exists $phash->[0]{bar}; # true, 'bar' is a valid field
exists $phash->[0]{shoes}; # false, 'shoes' can't be used
=head2 Function Templates