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 ANSI Common Lisp    12 Numbers    12.2 Dictionary of Numbers
 
 - Syntax:
 - 
1+
number
  
  successor
1-
number
    predecessor
 
  - Arguments and Values:
 - 
number - a number.
successor, predecessor - a number.
 
  - Description:
 - 
1+ returns a number that is one more than its argument number.
1- returns a number that is one less than its argument number.
  - Examples:
 - 
 (1+ 99)   100 
 (1- 100)   99 
 (1+ (complex 0.0))   #C(1.0 0.0) 
 (1- 5/3)   2/3 
 
  - Exceptional Situations:
 - 
Might signal type-error if its argument is not a number.
Might signal arithmetic-error.
  - See Also:
 - 
incf, decf
  - Notes:
 - 
 (1+ number) ==(+ number 1)
 (1- number) ==(- number 1)
 
Implementors are encouraged to make the performance of both the previous
expressions be the same.
  - Allegro CL Implementation Details:
 - 
 None.
  
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