Supramolecular protein polymers: When a heme moiety was introduced to the surface of an apo‐cytochrome b562(H63C) mutant, supramolecular polymers formed through noncovalent heme–hemepocketinteractions. The incorporation of a heme triad as a pivot molecule in the protein polymer further led to a two‐dimensional protein network structure, which was visualized by tapping‐mode atomic force microscopy