1. A method for executing a new command in a spreadsheet application, the method comprising: storing, in a storage device, instructions for implementing a declaration command, the declaration command assigning a command name as the new command with at least two parameters; and evaluating, by a processor, the declaration command in a first spreadsheet cell according to the instructions stored in the storage device, receiving, by the processor, the command name and at least two parameters identifying at least one input spreadsheet cell and at least one output spreadsheet cell of the spreadsheet application, creating, by the processor, a new command for the spreadsheet application, and evaluating, by the processor, the new command as identified by the command name in a second spreadsheet cell by providing input data to the at least one input spreadsheet cell and receive output data from the at least one output spreadsheet cell.