Module step function

A module should have a step function with this header step : ( t, substrates ) -> where t is the current time and substrates is an object with all the substrates. It should return an object with all the modified substrate deltas.

Example

Let's say you have four substrates and three modules:

Substrates

• enzym that breaks down food
• food outside
• food inside
• transporter enzym that transports food

cell = new Cell()
cell.add_substrate( 'enzym', 4 )
cell.add_substrate( 'food_out', 80 )
cell.add_substrate( 'food_in', 0 )
cell.add_substrate( 'transp', 0 )

Modules

• module that creates transporters from food
• module that transports food inside the cell
• module that breaks down food with enzym

	create_transport = new Module(
		{ rate: 2 }, 
		function ( t, substrates ) {
		    create = Math.min( this.rate, substrates.food_in )
			return { 'transp' : create, 
			 'food_in' : -create }
		}
	);

	transport_food = new Module(
		{ rate: 1, osmosis: .02 },
		function ( t, substrates ) {
			transporters = substrates.transp + this.osmosis
			food_out = substrates.food_out
			transport = Math.min( transporters * this.rate, Math.max( 0, food_out ) )
			return { 
				'food_out' : -transport, 
				'food_in' : transport 
			}
		}
	);

	food_enzym = new Module(
		{},
		function ( t, substrates ) {
			food_in = substrates.food_in
			enzym = substrates.enzym
			processed = Math.min( enzym, Math.max( 0, food_in ) )
			return { 
				'food_in' : -processed 
			}
		}
	);

	cell.add( create_transport ).add( transport_food ).add( food_enzym )

	cell.visualize( 30, $('.container'), { dt: 1 } )