code: def get(self, varname, idx=0, units=None):
          '''get a variable value'''
          if not varname in self.mapping.vars:
              raise fgFDMError('Unknown variable %s' % varname)
          if idx >= self.mapping.vars[varname].arraylength:
              raise fgFDMError('index of %s beyond end of array idx=%u arraylength=%u' % (
                  varname, idx, self.mapping.vars[varname].arraylength))
          value = self.values[self.mapping.vars[varname].index + idx]
          if units:
              value = self.convert(value, self.mapping.vars[varname].units, units)
          return valuf get(self, varname, idx=0, units=None):
          '''get a variable value'''
          if not varname in self.mapping.vars:
              raise fgFDMError('Unknown variable %s' % varname)
          if idx >= self.mapping.vars[varname].arraylength:
              raise fgFDMError('index of %s beyond end of array idx=%u arraylength=%u' % (
                  varname, idx, self.mapping.vars[varname].arraylength))
          value = self.values[self.mapping.vars[varname].index + idx]
          if units:
              value = self.convert(value, self.mapping.vars[varname].units, units)
          return value
docs: get a variable value