code: public FunctionHandle lookupFunction(String name, List<TypeSignatureProvider> parameterTypes)
      {
          return staticFunctionNamespace.lookupFunction(QualifiedName.of(name), parameterTypes);
      }
docs: Lookup up a function with name and fully bound types. This can only be used for builtin functions. {@link #resolveFunction(Session, QualifiedName, List)}
  should be used for dynamically registered functions.
  
  @throws PrestoException if function could not be found