first

Determines the first item type of a tuple or dictionary entry type.

This function may only be used with tuple or dictionary entry types, but must not be used with the generic tuple type `G_VARIANT_TYPE_TUPLE`.

In the case of a dictionary entry type, this returns the type of the key.

`NULL` is returned in case of this being `G_VARIANT_TYPE_UNIT`.

This call, together with [method@GLib.VariantType.next] provides an iterator interface over tuple and dictionary entry types.

Parameters:

this	a tuple or dictionary entry type

Returns:

the first item type of this, or `NULL` if the type has no item types Since 2.24