Look up the specified key and initialise an iterator to reference the associated metadata.
The iterator is used in conjunction with gegl_metadata_set_value and gegl_metadata_get_value. Note that this
iterator is not valid for iter_next.
| this |
The Metadata interface |
| iter |
MetadataIter to be initialised |
| key |
Name of the value look up |
|
true if key is found. |