In the sentence extracted from biomedical literature, identify all the chemical entities. The required answer format is the same sentence with HTML <span> tags to mark up specific entities. 
### Entity Markup Guides:
Use <span class="chemical"> to denote a chemical.

### Input Text: We conclude that the dipyridamole ECG test is as useful as the exercise ECG test for the assessment of coronary artery disease .
### Output Text:
We conclude that the <span class="chemical">dipyridamole</span> ECG test is as useful as the exercise ECG test for the assessment of coronary artery disease . 