 
 <prompt> Wetin be di word wey dey inside quotation? Based on di last question, write one context wey contain di answer. E fit be 1 - 20 sentences. Context: <response>: Classical statistical mechanics need h to dey exist (but e no define im value). Later on, based on top Planck discovery, dem come realize say physical action no fit just get any kain value. Instead, e must be some kind small quantity wey dey multiply by, wey dem dey call am "quantum of action", wey dem dey call am Planck constant now. Classical physics no fit explain dis fact. For many cases, like for monochromatic light or for atoms, dis quantum of action also mean say only certain energy levels dey allowed, and values wey dey in between dey forbidden. 