public boolean isSubroutineSymbol(Symbol s) {
		if (isBadReferenceSymbol(s)) {
			return false;
		}
		Reference[] refsTo = s.getReferences(null);
		for (Reference element : refsTo) {
			if (element.getReferenceType().isCall()) {
				return true;
			}
		}
		return false;
	}
Checks if the symbol is at the beginning of a subroutine.
@param s the symbol to check
@return boolean true if the symbol is at the beginning of a subroutine.
Ghidra/Features/Base/src/main/java/ghidra/app/util/SymbolInspector.java