sub alpha {
    my $self = shift;
    ...
    foreach ...
        if ...
            if ...
                if ...
                    push @foo, [ @bar ];
                }
            }
        } else {
            push @foo, [ @bar ];
        }
    }
    push @foo, [ @bar ];
    return \@foo;
}

sub beta {
    my $self = shift;
    ...
    foreach ...
        if ...
            if ...
                if ...
                    push @foo, [ @bar ] if $self->{baz} eq $gamma;
                }
            }
        } else {
            push @foo, [ @bar ] if $self->{baz} eq $gamma;
        }
    }
    push @foo, [ @bar ] if $self->{baz} eq $gamma;
    return \@foo;
}

##</code><code>##

    push @foo, [ @bar ];

##</code><code>##

    push @foo, [ @bar ] if $self->{baz} eq $gamma;

##</code><code>##

sub alpha {
    my $self = shift;
    my $coderef = sub {1};
    return $self->_internal_sub($coderef);
}

sub beta {
    my $self = shift;
    my $coderef = sub {$self->{baz} eq $gamma};
    return $self->_internal_sub($coderef);
}

sub _internal_sub {
    my $self = shift;
    my $coderef = shift;
    ...
    foreach ...
        if ...
            if ...
                if ...
                    push @foo, [ @bar ] if &$coderef;
                }
            }
        } else {
            push @foo, [ @bar ] if &$coderef;
        }
    }
    push @foo, [ @bar ] if &$coderef;
    return \@foo;
}