Given a single geohash, returns a lazy sequence of concentric square rings
of geohashes around it.  The first element is [hash], the second element is
[northern-neighbor, northwest-neighbor, west-neighbor, ...], the third
element is the list of all geohashes around *those*, and so on.

Creates a geohash from a string, or at the given point with the given bit
precision.

Returns the center point of a geohash.

Returns the error (i.e. the distance in meters between opposite corners) of
the given geohash.

Returns the maximum error (i.e. the distance between opposite corners of the
geohash bounding box) for a given number of geohash bits. Geohashes are least
precise at the equator.

An estimate of a geohash's area, in square meters, based on its midline
dimensions.

Returns a vector of [lat-extent long-extent], where lat-extent is the length
of the geohash through the midpoint of top and bottom, and long-extent is the
length of the geohash through the midpoint of left and right sides. All
figures in meters.

Returns a list of geohashes of the given precision within radius meters of
the given point.

Given a sequence of numbers in descending order, finds the index of the
largest number which is just greater than the target.

Estimates the precision which generates geohash regions on the scale of the
given shape.

Given a geohash at the northeast corner of a square (n-2) geohashes on a
side, returns a list of geohashes in a path around the square, such that the
first entry in the list is the northeast corner of a square (n) geohashes on
a side.

O is the origin argument
F is the first hash in the returned sequence
L is the last hash in the returned sequence
E represents the last *and* first in the sequence

n=1   3      5        7
                   +----LF
           +--LF   |    O|
     +LF   |  O|   |     |
  E  |O|   |   |   |     |
     +-+   |   |   |     |
           +---+   |     |
                   +-----+

If n is one, returns [origin].

This algorithm is undefined at the poles.

Returns the base32 encoded string value of a geohash.

Given a geohash, returns all geohashes inside it, of a given precision.

Given a geohash and a range of levels, return all geohashes inside the
given geohash at all the levels in the range