void showNewCallTree(Function function) {
		if (currentProgram == null) {
			return; // no program; cannot show tool
		}

		CallTreeProvider provider = findTransientProviderForLocation(function);
		if (provider != null) {
			tool.showComponentProvider(provider, true);
			return;
		}

		createAndShowProvider(function);
	}
Assuming a function <b>foo</b>, this plugin will show:
 1) all callers of <b>foo</b> 
 2) all functions which reference <b>foo</b>
 3) all callees of <b>foo</b>
 4) all functions referenced by <b>foo</b>.
Ghidra/Features/Base/src/main/java/ghidra/app/plugin/core/calltree/CallTreePlugin.java