sample.ps1xml

<?xml version="1.0" encoding="UTF-8"?>
<Types>
    <Type>
        <Name>System.Byte[]</Name>
        <Members>
            <ScriptProperty>
                <Name>Hex</Name>
                <GetScriptBlock>
                    $this | % {write-host $([String]::Format("{0:X}",$_)) -nonew}
                </GetScriptBlock>
            </ScriptProperty>
        </Members>
    </Type>
    <Type>
      <Name>System.IO.FileInfo</Name>
      <Members>
        <ScriptMethod>
          <Name>GetHash</Name>
          <Script>
            param([ValidateSet("SHA1","SHA256","SHA384","SHA512","MD5")]$Algorithm="SHA256")
            Get-FileHash $this.FullName $Algorithm
          </Script>
        </ScriptMethod>
        <ScriptProperty>
          <Name>Sha256</Name>
          <GetScriptBlock>
            $this.GetHash()
          </GetScriptBlock>
        </ScriptProperty>
        <ScriptProperty>
          <Name>MD5</Name>
          <GetScriptBlock>
            $this.GetHash("MD5")
          </GetScriptBlock>
        </ScriptProperty>
      </Members>
    </Type>
    <Type>
      <Name>System.Management.Automation.CommandInfo</Name>
      <Members>
        <ScriptProperty>
          <Name>Syntax</Name>
          <GetScriptBlock>($this | Get-Command -Syntax | Out-String).Trim()</GetScriptBlock>
        </ScriptProperty>
        <ScriptProperty>
          <Name>Synopsis</Name>
          <GetScriptBlock>($this | Get-Help).Synopsis.Trim()</GetScriptBlock>
        </ScriptProperty>
      </Members>
    </Type>
    <Type>
        <Name>Microsoft.PowerShell.Commands.MemberDefinition</Name>
        <Members>
            <ScriptProperty>
                <Name>HelpLink</Name>
                <GetScriptBlock>"http://msdn2.microsoft.com/library/$($this.typename).$($this.name).aspx"</GetScriptBlock>
            </ScriptProperty>
            <ScriptMethod>
                <Name>OpenHelpLink</Name>
                <Script>
                    Start-Process $this.HelpLink
                </Script>
            </ScriptMethod>
        </Members>
   </Type>
    <Type>
        <Name>System.String</Name>
        <Members>
            <ScriptMethod>
                <Name>ToBase64</Name>
                <Script>
                    [System.Convert]::ToBase64String([System.Text.Encoding]::UTF8.GetBytes($this))
                </Script>
            </ScriptMethod>
            <ScriptMethod>
                <Name>FromBase64</Name>
                <Script>
                    [System.Text.Encoding]::UTF8.GetString([System.Convert]::FromBase64String($this))
                </Script>
            </ScriptMethod>
        </Members>
    </Type>
    <Type>
        <Name>System.Security.SecureString</Name>
        <Members>
            <ScriptMethod>
                <Name>ToPlainText</Name>
                <Script>
                    $plaintext = ""
                    try {
                        $BSTR = [System.Runtime.InteropServices.marshal]::SecureStringToBSTR($this);
                        $plaintext = [System.Runtime.InteropServices.marshal]::PtrToStringAuto($BSTR);
                    } finally {
                        if($BSTR -ne [IntPtr]::Zero) {
                            [System.Runtime.InteropServices.Marshal]::ZeroFreeBSTR($BSTR);
                        }
                    }
                    Write-Output $plaintext
                </Script>
            </ScriptMethod>
        </Members>
    </Type>
    <Type>
        <Name>Microsoft.PowerShell.Commands.HistoryInfo</Name>
        <Members>
            <ScriptProperty>
                <Name>Duration</Name>
                <GetScriptBlock>
                    $this.EndExecutionTime - $this.StartExecutionTime
                </GetScriptBlock>
            </ScriptProperty>
        </Members>
    </Type>
</Types>