Minor code changes and add additional tests

Author: marijnvanwezel

README.md

@@ -33,13 +33,14 @@ To construct a query to find all of Tom Hanks' co-actors, you can use the
 following code:
 
 ```php
-$tom = Query::node("Person")->withProperties(["name" => "Tom Hanks"]);
-$coActors = Query::node();
+use function WikibaseSolutions\CypherDSL\node;
+use function WikibaseSolutions\CypherDSL\query;
 
-$statement = Query::new()
+$tom = node("Person")->withProperties(["name" => "Tom Hanks"]);
+$coActors = node();
+
+$statement = query()
     ->match($tom->relationshipTo(Query::node(), "ACTED_IN")->relationshipFrom($coActors, "ACTED_IN"))
     ->returning($coActors->property("name"))
     ->build();
-
-$this->assertStringMatchesFormat("MATCH (:Person {name: 'Tom Hanks'})-[:ACTED_IN]->()<-[:ACTED_IN]-(%s) RETURN %s.name", $statement);
 ```

src/Clauses/ReturnClause.php

@@ -61,7 +61,7 @@ public function addColumn(...$columns): self
     }
 
     /**
-     * Sets this query to only retrieve unique rows.
+     * Sets this query to only return unique rows.
      *
      * @return $this
      *

src/Clauses/UnionClause.php

@@ -27,35 +27,6 @@ final class UnionClause extends Clause
      */
     private bool $all = false;
 
-    /**
-     * Combines two queries with a union.
-     *
-     * @param Query $left  the query preceding the union clause
-     * @param Query $right the query after the union clause
-     * @param bool  $all   Whether the union should include all results or remove the duplicates instead.
-     *
-     *                     TODO: Move this function somewhere else.
-     */
-    public static function union(Query $left, Query $right, bool $all = false): Query
-    {
-        $tbr = Query::new();
-
-        foreach ($left->getClauses() as $clause) {
-            $tbr->addClause($clause);
-        }
-
-        $unionClause = new self();
-        $unionClause->setAll($all);
-
-        $tbr->addClause($unionClause);
-
-        foreach ($right->getClauses() as $clause) {
-            $tbr->addClause($clause);
-        }
-
-        return $tbr;
-    }
-
     /**
      * Sets that the union should include all results, instead of removing duplicates.
      *