<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def is_time_variable(varname, var):
 """ Identifies if a variable is represents time """

    satisfied = varname.lower() == 'time'
    satisfied |= getattr(var, 'standard_name', '') == 'time'
    satisfied |= getattr(var, 'axis', '') == 'T'
    satisfied |= units_convertible('seconds since 1900-01-01', getattr(var, 'units', ''))
    return satisfied