code: def numbered_matrix(nrows, ncols, symbol_prefix):
      return Matrix(
          nrows,
          ncols,
          lambda i, j: Symbol(
              symbol_prefix + "_{%d%d}" % (i + 1, j + 1)
          ),
      )
  
label_desc: Use image node_id 1 for calling a global function with example usage: numbered_matrix(nrows, ncols, symbol_prefix) and returns: Matrix