<Chapter><Heading> Pseudo lists</Heading>

<Table Align="|l|" >

<Row>
<Item>
<Index>Add</Index>
<C> Add(L,x)</C>


<P/>
Let <M>L</M> be a pseudo list of length <M>n</M>, and <M>x</M>
an object compatible with the entries in <M>L</M>.
If <M>x</M> is not in <M>L</M> then this operation converts  <M>L</M> 
into a pseudo list of length n+1 by adding  <M>x</M> as the 
final entry. If <M>x</M> is in <M>L</M> the operation has no effect on <M>L</M>.
</Item>
</Row>

<Row>
<Item>
<Index>Append</Index>
<C> Append(L,K)</C>


<P/>
Let <M>L</M> be a pseudo list  and <M>K</M> a list whose objects are compatible with those in <M>L</M>. This operation applies Add(L,x) for each x in <M>K</M>.  
</Item></Row>


<Row>
<Item>
<Index>ListToPseudoList</Index>
<C> ListToPseudoList(L)</C>


<P/>
Inputs a list <M>L</M> and returns the pseudo list representation of <M>L</M>.
</Item>
</Row>


</Table>
</Chapter>