/// <summary>
/// Add data to list.
/// </summary>
/// <param name='taxon'>Taxon to add.</param>
/// <returns>The list index at which the value has been added. -1 means has not been added.</returns>
public int Add(WebTaxon taxon)
{
if (taxon.IsNotNull())
{
int id = taxon.Id;
if (!_idHashTable.Contains(id))
{
_idHashTable.Add(id, taxon);
}
return(base.Add(taxon));
}
return(-1);
}
