prolog_xref:xref

xref_called(?Source, ?Called, ?By) is nondet

xref_called(?Source, ?Called, ?By, ?Cond) is nondet

xref_called(?Source, ?Called, ?By, ?Cond, ?Line) is nondet

True when By is called from Called in Source. Note that xref_called/3 and xref_called/4 use distinct/2 to return only distinct Called-By pairs. The xref_called/5 version may return duplicate Called-By if Called is called from multiple clauses in By, but at most one call per clause.

Arguments:

`By`	- is a head term or one of the reserved terms `'<directive>'(Line)` or `'<public>'(Line)`, indicating the call is from an (often initialization/1) directive or there is a public/1 directive that claims the predicate is called from in some untractable way.
`Cond`	- is the (accumulated) condition as defined by `:- if(Cond)` under which the calling code is compiled.
`Line`	- is the start line of the calling clause.