def get_value_of(value, model=nil)
      if value.kind_of? Symbol
        # If the function exist, we execute it
        if  model.respond_to? value
          return model.send value
        # if the the function not exist, whe set te symbol as a value
        else
          return value
        end
      elsif value.kind_of? Proc
        return value.call
      else
        return value
      end
    end
def get_value_of(value, model=nil)
      if value.kind_of? Symbol
        # If the function exist, we execute it
        if  model.respond_to? value
          return model.send value
        # if the the function not exist, whe set te symbol as a value
        else
          return value
        end
      elsif value.kind_of? Proc
        return value.call
      else
        return value
      end
    end
Return the value of the execute a function inside the model, for example:
 :column => :function
 this function execute the function _function_ to get the value and set it his return to column