title: How to use multiple union step in gremlin query?
body: <p>I want to convert following cypher query in gremlin but facing issue while using union.</p>
  <pre><code>match d=(s:Group{id:123})&lt;-[r:Member_Of*]-(p:Person) with d,
  RELATIONSHIPS(d) as rels
  WHERE NONE(rel in rels WHERE EXISTS(rel.`Ceased On`))
  return *
  
  UNION
  
  match d=(s:Group{id:123})&lt;-[r:Member_Of*]-(p:Group)-[r1:
  Member_Of*]-&gt;(c:Group) with d,
  RELATIONSHIPS(d) as rels
  WHERE NONE(rel in rels WHERE EXISTS(rel.`Ceased On`))
  return *
  
  UNION
  
  match d=(c:Group{id:123})-[r:Member_Of*]-&gt;(p:Group) with d,
  RELATIONSHIPS(d) as rels
  WHERE NONE(rel in rels WHERE EXISTS(rel.`Ceased On`))
  return *
  
  UNION
  
  match d=(s:Group{id:123})&lt;-[r:Member_Of*]-(p:Group)&lt;-[r1:
  Member_Of*]-(c:Person) with d,
  RELATIONSHIPS(d) as rels
  where NONE(rel in rels WHERE EXISTS(rel.`Ceased On`))
  return *
  </code></pre>
  <p>In above cypher query, source vertex is Group, which has id '123', so for incoming and outgoing edge, I have created following gremlin query.</p>
  <pre><code>g.V().hasLabel('Group').has('id',123)
   union(
     __.inE('Member_Of').values('Name'), 
     __.outE('Member_Of').values('Name'))
  .path()  
  </code></pre>
  <p>Now I have to traverse incoming edge for the vertex, which is incoming vertex for source vertex in above query, where I am confused with union syntax.</p>
  <p>Please help, Thanks :)</p>