anchor.diff:  date string ending with `||`. This anchor date can optionally be followed by
   one or more maths expressions:
   
  -* `+1h` - add one hour
  -* `-1d` - subtract one day
  -* `/d`  - round down to the nearest day
  +* `+1h`: Add one hour
  +* `-1d`: Subtract one day
  +* `/d`: Round down to the nearest day
   
   The supported time units differ from those supported by <<time-units, time units>> for durations.
   The supported units are:
   
   [horizontal]
  -`y`:: years
  -`M`:: months
  -`w`:: weeks
  -`d`:: days
  -`h`:: hours
  -`H`:: hours
  -`m`:: minutes
  -`s`:: seconds
  +`y`:: Years
  +`M`:: Months
  +`w`:: Weeks
  +`d`:: Days
  +`h`:: Hours
  +`H`:: Hours
  +`m`:: Minutes
  +`s`:: Seconds
   
   Assuming `now` is `2001-01-01 12:00:00`, some examples are:
   
  +[horizontal]
   `now+1h`:: `now` in milliseconds plus one hour. Resolves to: `2001-01-01 13:00:00`
   `now-1h`:: `now` in milliseconds minus one hour. Resolves to: `2001-01-01 11:00:00`
  -`now-1h/d`:: `now` in milliseconds minus one hour, rounded down to UTC 00:00. Resolves to: `2001-01-01 00:00:00``
  +`now-1h/d`:: `now` in milliseconds minus one hour, rounded down to UTC 00:00. Resolves to: `2001-01-01 00:00:00`
    `2001.02.01\|\|+1M/d`:: `2001-02-01` in milliseconds plus one month. Resolves to: `2001-03-01 00:00:00`
   
   [float]
  
positive.code: `static_name`:: is the static text part of the name
  `date_math_expr`:: is a dynamic date math expression that computes the date dynamically
  `date_format`:: is the optional format in which the computed date should be rendered. Defaults to `YYYY.MM.dd`.
  `time_zone`:: is the optional time zone . Defaults to `utc`.
  
  Date math expressions are resolved locale-independent. Consequently, it is not possible to use any other
  calendars than the Gregorian calendar.
  
negative.code: === Human readable output
  
  Statistics are returned in a format suitable for humans
  (e.g. `"exists_time": "1h"` or `"size": "1kb"`) and for computers
  (e.g. `"exists_time_in_millis": 3600000` or `"size_in_bytes": 1024`).
  The human readable values can be turned off by adding `?human=false`
  to the query string. This makes sense when the stats results are
  being consumed by a monitoring tool, rather than intended for human
  