code: def get(self, get_params, block):
          
          value = "{%s}" % self.key
          try:
              value = value_ = get_params(self.key)
              if self.format.startswith(":"):
                  # if a parameter has been set to be formatted as a numeric
                  # type then we see if we can coerce it to be.  This allows
                  # the user to format types that normally would not be
                  # allowed eg '123' it also allows {:d} to be used as a
                  # shorthand for {:.0f}.  Use {:g} to remove insignificant
                  # trailing zeroes and the decimal point too if there are
                  # no remaining digits following it.  If the parameter cannot
                  # be successfully converted then the format will be removed.
                  try:
                      if "ceil" in self.format:
                          value = int(ceil(float(value)))
                      if "f" in self.format:
                          value = float(value)
                      if "g" in self.format:
                          value = float(value)
                      if "d" in self.format:
                          value = int(float(value))
                      output = u"{[%s]%s}" % (self.key, self.format)
                      value = output.format({self.key: value})
                      value_ = float(value)
                  except ValueError:
                      pass
              elif self.format.startswith("!"):
                  output = u"{%s%s}" % (self.key, self.format)
                  value = value_ = output.format(**{self.key: value})
  
              if block.commands.not_zero:
                  valid = value_ not in ["", None, False, "0", "0.0", 0, 0.0]
              else:
                  # '', None, and False are ignored
                  # numbers like 0 and 0.0 are not.
                  valid = not (value_ in ["", None] or value_ is False)
              enough = False
          except:  # noqa e722
              # Exception raised when we don't have the param
              enough = True
              valid = False
  
          return valid, value, enough
docs: return the correct value for the placeholder