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A multi-dimensional ``Vector`` class, take 1
A ``Vector`` is built from an iterable of numbers::
    >>> Vector([3.1, 4.2])
    Vector([3.1, 4.2])
    >>> Vector((3, 4, 5))
    Vector([3.0, 4.0, 5.0])
    >>> Vector(range(10))
    Vector([0.0, 1.0, 2.0, 3.0, 4.0, ...])
Tests with 2-dimensions (same results as ``vector2d_v1.py``)::
    >>> v1 = Vector([3, 4])
    >>> x, y = v1
    >>> x, y
    (3.0, 4.0)
    Vector([3.0, 4.0])
    >>> v1_clone = eval(repr(v1))
    >>> v1 == v1_clone
    >>> print(v1)
    (3.0, 4.0)
    >>> octets = bytes(v1)
    >>> octets
    b'd\\x00\\x00\\x00\\x00\\x00\\x00\\x08@\\x00\\x00\\x00\\x00\\x00\\x00\\x10@'
    >>> abs(v1)
    >>> bool(v1), bool(Vector([0, 0]))
    (True, False)
Test of ``.frombytes()`` class method:
    >>> v1_clone = Vector.frombytes(bytes(v1))
    >>> v1_clone
    Vector([3.0, 4.0])
    >>> v1 == v1_clone
Tests with 3-dimensions::
    >>> v1 = Vector([3, 4, 5])
    >>> x, y, z = v1
    >>> x, y, z
    (3.0, 4.0, 5.0)
    Vector([3.0, 4.0, 5.0])
    >>> v1_clone = eval(repr(v1))
    >>> v1 == v1_clone
    >>> print(v1)
    (3.0, 4.0, 5.0)
    >>> abs(v1)  # doctest:+ELLIPSIS
    7.071067811...
    >>> bool(v1), bool(Vector([0, 0, 0]))
    (True, False)
Tests with many dimensions::
    >>> v7 = Vector(range(7))
    Vector([0.0, 1.0, 2.0, 3.0, 4.0, ...])
    >>> abs(v7)  # doctest:+ELLIPSIS
    9.53939201...
Test of ``.__bytes__`` and ``.frombytes()`` methods::
    >>> v1 = Vector([3, 4, 5])
    >>> v1_clone = Vector.frombytes(bytes(v1))
    >>> v1_clone
    Vector([3.0, 4.0, 5.0])
    >>> v1 == v1_clone
# tag::VECTOR_V1[]
from array import array
import reprlib
import math
class Vector:
    typecode = 'd'
    def __init__(self, components):
        self._components = array(self.typecode, components)  # <1>
    def __iter__(self):
        return iter(self._components)  # <2>
    def __repr__(self):
        components = reprlib.repr(self._components)  # <3>
        components = components[components.find('['):-1]  # <4>
        return f'Vector({components})'
    def __str__(self):
        return str(tuple(self))
    def __bytes__(self):
        return (bytes([ord(self.typecode)]) +
                bytes(self._components))  # <5>
    def __eq__(self, other):
        return tuple(self) == tuple(other)
    def __abs__(self):
        return math.hypot(*self)  # <6>
    def __bool__(self):
        return bool(abs(self))
    @classmethod
    def frombytes(cls, octets):
        typecode = chr(octets[0])
        memv = memoryview(octets[1:]).cast(typecode)
        return cls(memv)  # <7>
# end::VECTOR_V1[]

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