parameters: (key)
return_statement: return physical_constants[key][2] / physical_constants[key][0]
docstring: Relative precision in physical_constants indexed by key
  
      Parameters
      ----------
      key : Python string or unicode
          Key in dictionary `physical_constants`
  
      Returns
      -------
      prec : float
          Relative precision in `physical_constants` corresponding to `key`
  
      See Also
      --------
      codata : Contains the description of `physical_constants`, which, as a
          dictionary literal object, does not itself possess a docstring.
  
      Examples
      --------
      >>> from scipy import constants
      >>> constants.precision(u'proton mass')
      1.2555138746605121e-08
docstring_summary: Relative precision in physical_constants indexed by key
docstring_tokens: Relative precision in physical_constants indexed by key
function: def precision(key):
      """
      Relative precision in physical_constants indexed by key
  
      Parameters
      ----------
      key : Python string or unicode
          Key in dictionary `physical_constants`
  
      Returns
      -------
      prec : float
          Relative precision in `physical_constants` corresponding to `key`
  
      See Also
      --------
      codata : Contains the description of `physical_constants`, which, as a
          dictionary literal object, does not itself possess a docstring.
  
      Examples
      --------
      >>> from scipy import constants
      >>> constants.precision(u'proton mass')
      1.2555138746605121e-08
  
      """
      _check_obsolete(key)
      return physical_constants[key][2] / physical_constants[key][0]
function_tokens: def precision ( key ) : _check_obsolete ( key ) return physical_constants [ key ] [ 2 ] / physical_constants [ key ] [ 0 ]