anchor.diff:  For any requested location a relevant station is computed.
   To the relevant station, the distance and available parameters are taken into concern.
   
  +HINT:
  +* all timestamps are meant to be UTC, or in a request provide correct offset (so that server can convert to UTC.)
  +* in response, timestamps are also returned as UTC
  +   * if we foresee in future returning e.g. 'observedFrom' in local time zone, than I propose "observedFromInLocalTime" to be more explicit.
  +
   + Parameters
       + locatedAt: `13.37788,52.5337` (string, required) - longitude,latitude; can occur multiple times for multiple stations
       + locatedAt: `joionluqqFvwqmo629nC` (string, optional) - compressed list of station locations, using Microsoft Point Compression Algorithm, is efficient for up to 400 locations
       + fields: `sunshineDurationInMinutes,airTemperatureInCelsius` (string, required) - comma separated list of parameters to be contained inside response
  -    + observedFromUtc: `2016-10-13T11:00:00Z` (string, optional)
  -    + observedUntilUtc: `2016-10-13T15:00:00Z` (string, optional)
  -    + observedFromLocalTime: `2016-10-13T11:00:00Z` (string, optional)
  -    + observedUntilLocalTime: `2016-10-13T15:00:00Z` (string, optional)
  +    + observedFrom: `2016-10-13T11:00:00Z` (string, optional)
  +    + observedUntil: `2016-10-13T15:00:00Z` (string, optional)
       + observedPeriod: `PT0S,PT1H,PT12H` (string, required) - comma separated list of periods to be retrieved. use iso8601 time duration notation. PT0S refers to observations at a moment in time. PT1H applies one hour aggregation.
   
   + Response 200 (application/json)
  
positive.code:                     }
                  ]
              }
  
  # Group Forecast
  
  
negative.code: ## Retrieve weather observation [/observation?locatedAt={locatedAt}&fields={fields}&]
  
  #### Example
  `https://api.weather.mg/observation?location=53,13`  to be fixed ...
  
  ### Observed weather for a given *latitude* and *longitude* [GET]
  
  