The `PangoAttribute` structure represents the common portions of all attributes.
Particular types of attributes include this structure as their initial portion. The common portion of the attribute holds the range to
which the value in the type-specific part of the attribute applies and should be initialized using [[email protected]]. By
default, an attribute will have an all-inclusive range of [0,g_maxuint].
Initializes this's klass to
klass, it's start_index to pango_attr_index_from_text_beginning and end_index to
pango_attr_index_to_text_end such that the attribute applies to the entire text by default.