The Vector class of Section 2.3.3 provides a constructor that takes an integer
d, and produces a d-dimensional vector with all coordinates equal to
0. Another convenient form for creating a new vector would be to send the
constructor a parameter that is some iterable type representing a sequence
of numbers, and to create a vector with dimension equal to the length of
that sequence and coordinates equal to the sequence values. For example,
Vector([4, 7, 5]) would produce a three-dimensional vector with coordinates
. Modify the constructor so that either of these forms is
acceptable; that is, if a single integer is sent, it produces a vector of that
dimension with all zeros, but if a sequence of numbers is provided, it produces
a vector with coordinates based on that sequence.