code: @Nonnull
    public EChange removeVariable (@Nullable final String sName)
    {
      if (sName == null)
        return EChange.UNCHANGED;
      return m_aMap.removeObject (sName);
    }
docs: Remove the variable with the specified name.
  
  @param sName
  The name to be removed. May be <code>null</code>.
  @return {@link EChange}