Updates to Grist Functions (#125)

Clarify documentation for QUOTIENT, SUMPRODUCT, UUID, REPLACE, lookupOne, lookupRecords, and $group.

sandbox/grist/functions/math.py

@@ -550,7 +550,7 @@ def PRODUCT(factor1, *more_factors):
 
 def QUOTIENT(dividend, divisor):
   """
-  Returns one number divided by another.
+  Returns one number divided by another, without the remainder.
 
   >>> QUOTIENT(5, 2)
   2
@@ -797,7 +797,8 @@ def SUMIFS(sum_range, criteria_range1, criterion1, *args):
 
 def SUMPRODUCT(array1, *more_arrays):
   """
-  Multiplies corresponding components in the given arrays, and returns the sum of those products.
+  Multiplies corresponding components in two equally-sized arrays, 
+  and returns the sum of those products.
 
   >>> SUMPRODUCT([3,8,1,4,6,9], [2,6,5,7,7,3])
   156
@@ -859,7 +860,13 @@ def TRUNC(value, places=0):
   return ROUNDDOWN(value, places)
 
 def UUID():
-  """Generate a random UUID-formatted string identifier."""
+  """
+  Generate a random UUID-formatted string identifier. 
+  Since UUID() produces a different value each time it's called, it is best to use it in 
+  [trigger formula](https://support.getgrist.com/formulas/#trigger-formulas) for new records. 
+  This would only calculate UUID() once and freeze the calculated value. By contrast, a regular [formula] 
+  may get recalculated any time the document is reloaded, producing a different value for UUID() each time.
+  """
   if six.PY2:
     return str(uuid.UUID(bytes=[chr(random.randrange(0, 256)) for _ in xrange(0, 16)], version=4))
   else: