gistfile1.py

#you have this
class Note(db.Model):
    """ user note on a cell """
    cell = db.ReferenceProperty(Cell)

#Instead, do this,
class Note(db.Model):
    """ user note on a cell """
    #parent = Cell #this is done on creation
    cell = db.ReferenceProperty(collection='notes', Cell)

"""
What this will allow is a bit more useful, you can drop the RefProp 
entirely if you'd never use it.
"""

#So 
Note.parent() #would return the cell like Node.cell would have, but now
Cell.notes    #will return all the notes that have been applied to it.


"""Another quick one"""
#create a structure capable for search by just the key for Cells
class Cell(db.Model):
   #key = 'z/x/y/year/month/day' #if a cell is unique for each day
   #or
   #key = 'z/x/y/report_id' #if a cell is unique for each report