def cid
      pug_uri = "https://pubchem.ncbi.nlm.nih.gov/rest/pug/"
      update(:cid => RestClientWrapper.post(File.join(pug_uri, "compound", "inchi", "cids", "TXT"),{:inchi => inchi}).strip) unless self["cid"] 
      self["cid"]
    end
def cid
      pug_uri = "https://pubchem.ncbi.nlm.nih.gov/rest/pug/"
      update(:cid => RestClientWrapper.post(File.join(pug_uri, "compound", "inchi", "cids", "TXT"),{:inchi => inchi}).strip) unless self["cid"] 
      self["cid"]
    end
Get PubChem Compound Identifier (CID), obtained via REST call to PubChem
 @return [String]