docs: def geometry(AA):
      '''Generates the geometry of the requested amino acid.
      The amino acid needs to be specified by its single-letter
      code. If an invalid code is specified, the function
      returns the geometry of Glycine.'''
      if(AA=='G'):
          return GlyGeo()
      elif(AA=='A'):
          return AlaGeo()
      elif(AA=='S'):
          return SerGeo()
      elif(AA=='C'):
          return CysGeo()
      elif(AA=='V'):
          return ValGeo()
      elif(AA=='I'):
          return IleGeo()
      elif(AA=='L'):
          return LeuGeo()
      elif(AA=='T'):
          return ThrGeo()
      elif(AA=='R'):
          return ArgGeo()
      elif(AA=='K'):
          return LysGeo()
      elif(AA=='D'):
          return AspGeo()
      elif(AA=='E'):
          return GluGeo()
      elif(AA=='N'):
          return AsnGeo()
      elif(AA=='Q'):
          return GlnGeo()
      elif(AA=='M'):
          return MetGeo()
      elif(AA=='H'):
          return HisGeo()
      elif(AA=='P'):
          return ProGeo()
      elif(AA=='F'):
          return PheGeo()
      elif(AA=='Y'):
          return TyrGeo()
      elif(AA=='W'):
          return TrpGeo()
      else:
          return GlyGeo()