code: def param(type):
      
      import ibis.expr.datatypes as dt
      import ibis.expr.operations as ops
  
      return ops.ScalarParameter(dt.dtype(type)).to_expr()
docs: Create a parameter of a particular type to be defined just before
      execution.
  
      Parameters
      ----------
      type : dt.DataType
          The type of the unbound parameter, e.g., double, int64, date, etc.
  
      Returns
      -------
      ScalarExpr
  
      Examples
      --------
      >>> import ibis
      >>> import ibis.expr.datatypes as dt
      >>> start = ibis.param(dt.date)
      >>> end = ibis.param(dt.date)
      >>> schema = [('timestamp_col', 'timestamp'), ('value', 'double')]
      >>> t = ibis.table(schema)
      >>> predicates = [t.timestamp_col >= start, t.timestamp_col <= end]
      >>> expr = t.filter(predicates).value.sum()