static FunctionDefinition editSignature(DecompilerActionContext context, Function calledFunc,
			String signature) {
		Function func = context.getFunction();
		Program program = func.getProgram();
		PluginTool tool = context.getTool();

		String conv = program.getCompilerSpec().getDefaultCallingConvention().getName();
		if (calledFunc != null) {
			conv = calledFunc.getCallingConventionName();
		}

		ProtoOverrideDialog dialog =
			new ProtoOverrideDialog(tool, calledFunc != null ? calledFunc : func, signature, conv);
		tool.showDialog(dialog);
		return dialog.getFunctionDefinition();
	}
Try to find the PcodeOp representing the call the user has selected
@param program is the Program
@param tokenAtCursor is the point in the window the user has selected
@return the PcodeOp or null
Ghidra/Features/Decompiler/src/main/java/ghidra/app/plugin/core/decompile/actions/OverridePrototypeAction.java