pub fn seq_begin(&mut self) -> Result<Pos, crate::Error> {
        const MASK: u8 = Slot::MASK_SLOT & Slot::NEEDS_ITEM;
        const VALID: u8 = Slot::NEEDS_ITEM;
        const EXPECT: RawStack = (Slot::NEEDS_SEQ_ELEM) as RawStack;

        if self.depth == Self::MAX_DEPTH {
            return Err(crate::Error::custom(
                &"more depth at the start of a sequence",
            ));
        }

        if self.inner as u8 & MASK == VALID {
            self.inner = (self.inner << Slot::BITS) & Self::MASK_SLOT_BEGIN | EXPECT;
            self.depth += 1;

            Ok(Pos(self.inner, self.depth))
        } else {
            Err(crate::Error::custom(&"the start of a sequence"))
        }
    }
/**
    Begin a new sequence.

    the sequence must be completed by calling `seq_end`.
    */
Begin a new sequence.
the sequence must be completed by calling `seq_end`.
Begin a new sequence . the sequence must be completed by calling ` seq_end ` .
pub fn seq_begin(&mut self) -> Result<Pos, crate::Error> {
        const MASK: u8 = Slot::MASK_SLOT & Slot::NEEDS_ITEM;
        const VALID: u8 = Slot::NEEDS_ITEM;
        const EXPECT: RawStack = (Slot::NEEDS_SEQ_ELEM) as RawStack;
        if self.depth == Self::MAX_DEPTH {
            return Err(crate::Error::custom(
                &"more depth at the start of a sequence",
            ));
        }
        if self.inner as u8 & MASK == VALID {
            self.inner = (self.inner << Slot::BITS) & Self::MASK_SLOT_BEGIN | EXPECT;
            self.depth += 1;
            Ok(Pos(self.inner, self.depth))
        } else {
            Err(crate::Error::custom(&"the start of a sequence"))
        }
    }
pub fn seq_begin ( & mut self ) -> Result < Pos , crate :: Error > { const MASK : u8 = Slot :: MASK_SLOT & Slot :: NEEDS_ITEM ; const VALID : u8 = Slot :: NEEDS_ITEM ; const EXPECT : RawStack = ( Slot :: NEEDS_SEQ_ELEM ) as RawStack ; if self . depth == Self :: MAX_DEPTH { return Err ( crate :: Error :: custom ( & " " , ) ) ; } if self . inner as u8 & MASK == VALID { self . inner = ( self . inner << Slot :: BITS ) & Self :: MASK_SLOT_BEGIN | EXPECT ; self . depth += 1 ; Ok ( Pos ( self . inner , self . depth ) ) } else { Err ( crate :: Error :: custom ( & " " ) ) } }
Begin a new sequence.
Begin a new sequence .
&mut self