mekso at-most-4-ary operator: integer lattice ball; the set of all points belonging to the intersection of Zn with the closure of the ball that is centered on X1 and has radius X2 in metric X3, where Z is the set of all integers and where, for any set A and non-negative integer n, An is the set of all n-tuples such that each coordinate/entry/term belongs to A, and where the dimensionality n = X4..
X3 defaults to whatsoever metric is specified to apply but which is outside of this function; contextless default is discrete, taxicab, Euclidean, or Chebyshev maximum norm; for explicit specification, use "mau'au"-"zai'ai" quotation. X2 defaults to 1. X1 defaults to 0 = (0,...,0), where the rhs is an X4-tuple, id est the origin. See also: "mi'i", "ci'au'u".