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        <link:usedOn>link:definitionLink</link:usedOn>
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  <xs:element id="gral_SpinoffTransactionNumberOfSharesRetained" abstract="false" name="SpinoffTransactionNumberOfSharesRetained" nillable="true" xbrli:periodType="instant" substitutionGroup="xbrli:item" type="xbrli:sharesItemType"/>
  <xs:element id="gral_NoncontrollingInterestSaleOfOwnedSharesShares" abstract="false" name="NoncontrollingInterestSaleOfOwnedSharesShares" nillable="true" xbrli:periodType="instant" substitutionGroup="xbrli:item" type="xbrli:sharesItemType"/>
  <xs:element id="gral_NoncontrollingInterestNumberOfSharesOutstanding" abstract="false" name="NoncontrollingInterestNumberOfSharesOutstanding" nillable="true" xbrli:periodType="instant" substitutionGroup="xbrli:item" type="xbrli:sharesItemType"/>
  <xs:element id="gral_SuppliesCurrent" abstract="false" name="SuppliesCurrent" nillable="true" xbrli:periodType="instant" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="gral_ShareBasedCompensationByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsAggregateGrantDateFairValue" abstract="false" name="ShareBasedCompensationByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsAggregateGrantDateFairValue" nillable="true" xbrli:periodType="instant" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="gral_Mr.JoshOfmanMember" abstract="true" name="Mr.JoshOfmanMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="gral_Mr.AaronFreidinMember" abstract="true" name="Mr.AaronFreidinMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
</xs:schema>
