I have an xsl variable that looks like this:

```
<xsl:variable name="all" >
    abab
</xsl:variable>

```

Now I want to compute the length of the above variable (`all`) so I try to do this:

```
<xsl:value-of select="string-length($all)"/>

```

I expect 4 to be my answer (4 characters in the string 'abab') but I get 39.

What am I doing wrong here?