add helper functions to CvAttribute Collection

src/ArcGraphModel/CvTokens/CvAttributeCollection.fs

@@ -88,9 +88,23 @@ type CvAttributeCollection(attributes : IDictionary<string,IParam>) =
             ac.TryGetAttribute name
         | _ -> None
 
-    /// Returns true, if it implements a CvAttributeCollection and the attribute exists, else returns None
+    /// Returns the attribute of the value, if it implements CvAttributeCollection and the attribute exists, else returns None
+    static member tryGetAttributeByTerm (term : string) (v : IAttributeCollection) =
+        match box v with
+        | :? CvAttributeCollection as ac -> 
+            ac.TryGetAttribute term
+        | _ -> None
+
+    /// Returns true, if it implements a CvAttributeCollection and the attribute exists
     static member containsAttribute (name : string) (v : IAttributeCollection) =
         match box v with
         | :? CvAttributeCollection as ac -> 
             ac.ContainsAttribute name
+        | _ -> false
+
+    /// Returns true, if it implements a CvAttributeCollection and the attribute exists
+    static member containsAttributeTerm (term : CvTerm) (v : IAttributeCollection) =
+        match box v with
+        | :? CvAttributeCollection as ac -> 
+            ac.ContainsAttribute term
         | _ -> false

src/ArcGraphModel/CvTokens/CvParam.fs

@@ -27,11 +27,15 @@ type CvParam(cvAccession : string, cvName : string, cvRefUri : string, paramValu
         CvParam (id,name,ref,pv,dict)
     new (id,name,ref,pv) = 
         CvParam (id,name,ref,pv,Seq.empty)
+    new (id,name,ref,v : IConvertible) = 
+        CvParam (id,name,ref,ParamValue.Value v)
 
     new ((id,name,ref) : CvTerm,pv,attributes : seq<IParam>) = 
         CvParam (id,name,ref,pv,attributes)
     new (cvTerm,pv : ParamValue) = 
         CvParam (cvTerm,pv,Seq.empty)
+    new (cvTerm,v : IConvertible) = 
+        CvParam (cvTerm,ParamValue.Value v)
 
     member this.Equals (term : CvTerm) = 
         CvBase.equalsTerm term this

src/ArcGraphModel/CvTokens/CvTerm.fs

@@ -18,6 +18,11 @@ module CvTerm =
         match cvTerm with
         | id, name, refUri -> id
 
+    /// gets the source reference of the CvTerm
+    let getRef (cvTerm : CvTerm) = 
+        match cvTerm with
+        | id, name, refUri -> refUri
+
     /// creates a CvTerm from name
     let fromName (name : string) : CvTerm= 
         "", name, ""