Accessor to the variable length metalayers.

This class inherits from the MutableMapping class, so every method in this class is available. It behaves very similarly to a dictionary, and variable length metalayers can be appended in the typical way:

schunk.vlmeta['vlmeta1'] = 'something'

And can be retrieved similarly:

value = schunk.vlmeta['vlmeta1']

Once added, a vlmeta can be deleted with:

del schunk.vlmeta['vlmeta1']

Moreover, a getall() method returns all the variable length metalayers as a dictionary.