[xsl] What is a bulletproof way to assign a variable this value: single quote, value of an element, single quote?

["Roger L Costello costello@xxxxxxxxx" <xsl-list-service@xxxxxxxxxxxxxxxxxxxxxx>]

Hi Folks,

The value of $legacy-elmt is this element:

      <test>Hello, world</test>

Create a variable which holds between single quotes the value of the element
that $legacy-elmt holds. Do this using a two-step process:

<xsl:variable name="tmp-legacy-elmt-value" as="xs:string+">
            <xsl:text>'</xsl:text>
            <xsl:value-of select="string($legacy-elmt)"/>
            <xsl:text>'</xsl:text>
</xsl:variable>

<xsl:variable name="legacy-elmt-name" as="xs:string">
            <xsl:value-of select="$tmp-legacy-elmt-value" separator=""/>
 </xsl:variable>

$legacy-elmt-value = 'Hello, world'

That appears to work flawlessly, right?

Not so fast.

Suppose the value of $legacy-elmt is this element:

      <test>O'Neil</test>

$legacy-elmt-value = 'O'Neil'

That is an error (unmatched single quote).

What is the best way to fix this error?

/Roger