How to use cascading.operation.expression

public String getExpression()
 {
 return getBlock();
 }

public String getScript()
 {
 return getBlock();
 }

private Fields getParameterFields()
 {
 return makeFields( getParameterNamesInternal() );
 }

private Object evaluate( ExpressionFunction function, TupleEntry tupleEntry )
 {
 TupleListCollector tuples = invokeFunction( function, tupleEntry, function.getFieldDeclaration() );
 return tuples.entryIterator().next().getObject( 0 );
 }

private void assertFail( ValueAssertion assertion, TupleEntry tupleEntry )
 {
 ConcreteCall concreteCall = getOperationCall( tupleEntry );
 assertion.prepare( FlowProcess.NULL, concreteCall );
 try
  {
  assertion.doAssert( FlowProcess.NULL, concreteCall );
  fail();
  }
 catch( AssertionException exception )
  {
  // do nothing
  }
 }

public String getScript()
 {
 return getBlock();
 }

public String getScript()
 {
 return getBlock();
 }

private void assertPass( ValueAssertion assertion, TupleEntry tupleEntry )
 {
 ConcreteCall concreteCall = getOperationCall( tupleEntry );
 assertion.prepare( FlowProcess.NULL, concreteCall );
 assertion.doAssert( FlowProcess.NULL, concreteCall );
 }

@Override
public boolean isRemove( FlowProcess flowProcess, FilterCall<Context> filterCall )
 {
 return (Boolean) evaluate( filterCall.getContext(), filterCall.getArguments() );
 }
}

@Override
public boolean isRemove( FlowProcess flowProcess, FilterCall<Context> filterCall )
 {
 return (Boolean) evaluate( filterCall.getContext(), filterCall.getArguments() );
 }
}

private Fields getParameterFields()
 {
 return makeFields( getParameterNamesInternal() );
 }

private Object evaluate( ExpressionFunction function, TupleEntry tupleEntry )
 {
 TupleListCollector tuples = invokeFunction( function, tupleEntry, function.getFieldDeclaration() );
 return tuples.entryIterator().next().getObject( 0 );
 }

private void assertFail( ValueAssertion assertion, TupleEntry tupleEntry )
 {
 ConcreteCall concreteCall = getOperationCall( tupleEntry );
 assertion.prepare( FlowProcess.NULL, concreteCall );
 try
  {
  assertion.doAssert( FlowProcess.NULL, concreteCall );
  fail();
  }
 catch( AssertionException exception )
  {
  // do nothing
  }
 }

public String getExpression()
 {
 return getBlock();
 }

public String getScript()
 {
 return getBlock();
 }

public String getScript()
 {
 return getBlock();
 }

public String getScript()
 {
 return getBlock();
 }

private void assertPass( ValueAssertion assertion, TupleEntry tupleEntry )
 {
 ConcreteCall concreteCall = getOperationCall( tupleEntry );
 assertion.prepare( FlowProcess.NULL, concreteCall );
 assertion.doAssert( FlowProcess.NULL, concreteCall );
 }

@Override
public boolean isRemove( FlowProcess flowProcess, FilterCall<Context> filterCall )
 {
 return (Boolean) evaluate( filterCall.getContext(), filterCall.getArguments() );
 }
}

@Override
public boolean isRemove( FlowProcess flowProcess, FilterCall<Context> filterCall )
 {
 return (Boolean) evaluate( filterCall.getContext(), filterCall.getArguments() );
 }
}